1. Field of the Invention
The present invention relates to a wristwatch used while being worn to a human body's arm by using a band, and the band for the wristwatch detachably attached to a case band of this wristwatch.
2. Description of the Related Art
Hitherto, in an attachment of the band to the case band of the wristwatch, it is general to use a so-called spring bar. The spring bar is formed with two stepped pins and a coil spring being accommodated in a tube whose both ends parts are reduced. A small diameter axle part that the stepped pin has is protruded from an end of the tube, and inserted into an attachment hole bored in a protrusion part (bow foot) of the case band. By it, the band is connected to the case band. The coil spring is nipped between the two stepped pins, and biases these stepped pins in mutually reverse directions. Accordingly, by push-operating this stepped pin to the tube to thereby be removed from the attachment hole, it is possible to detach the band from the case band (e.g., refer to JP-A-61-154604 Gazette (Paragraph of Detailed Description of the Invention, FIG. 1-FIG. 4)).
Additionally, there is known a technique in which an attachment/detachment of the and in regard to the case band is made possible by moving a stepped connection axle, in which small diameter parts are protrusively provided in both ends of a large diameter part whose diameter matches with the attachment hole of the protrusion part (bow foot) of the case band, in a direction along which adjoining protrusion parts queue while forming a bow crotch receiving an end part of the band, thereby causing it to penetrate through the attachment hole of one protrusion part (bow foot) (e.g., refer to JP-A-61-154604 Gazette (Paragraph of Detailed Description of the Invention, FIG. 1-FIG. 4)).
Further, there is also known a technique in which, in order that the spring bar can be operated by bare hands when attaching/detaching the band to/from the case band, there is provided, in one expansion/contraction axle part protruded from one end of a spring bar main body, a protrusion making it possible to operate this axle part by the bare hands. There is also known the fact that, in this case, a notch is provided in an end part of an end piece of a metal-made band, and the above protrusion for the operation can be accommodated in this notch (e.g., refer to Microfilm of Utility Model Application No. Sho 60-1070446 (JP-UM-A-62-79419) (Paragraph of Detailed Description of the Device, FIG. 1-FIG. 3)).
In the technique of JP-A-61-154604 Gazette, in which there is used the spring bar or the technique in which there is used the stepped connection axle, since an exclusive tool is required in order to remove the spring bar or the stepped connection axle from the protrusion part (bow foot) of the case band, an operation when detaching the band is troublesome. Therefore, as to a band exchange, a difficulty is high for a user having near no tool.
Additionally, in the technique of JP-A-61-154604 Gazette, in which there is used the stepped connection axle, in addition to the fact that a thickness of the small diameter part of this axle is made a thickness exhibiting a predetermined strength such that this small diameter part is not bent easily, the attachment hole of the protrusion part (bow foot) must be formed large such that the large diameter part, whose thickness is additionally thicker than the last-mentioned thickness, can be inserted/retracted. Therefore, it is not only disadvantageous in thinning the case band, but also a reduction in commodity property is brought about because the band easily, loosely moves especially in a 12 o'clock-6 o'clock direction resulting from the fact that a large clearance is formed between the large diameter attachment hole and the small diameter part of the stepped connection axle. Additionally, since the stepped connection axle is not held to the band, a fear that an existence of the stepped connection axle becomes unclear during custody of the band is high.
In the technique of Microfilm of Utility Model Application No. Sho 60-1070446 (JP-UM-A-62-79419), although there is provided a manually operating protrusion for release-operating the spring bar, unless this protrusion is made thinner than a thickness of an attachment leg (bow foot) of the case band, a possibility that the protrusion beats against a wrist of the user in an ordinary use becomes high. Therefore, it is unavoidable that the protrusion becomes inevitably small. Moreover, the above protrusion is disposed so as to be nipped between an end part side face of the band and a side face of the attachment leg of the case band. Accordingly, manually operating the above protrusion accompanies actually a considerable difficulty, and rather using the exclusive tool is much easier to operate.